Glomus Tumor as a Cause of Severe Thigh Pain

Introduction

Glomus tumor is a relatively rare tumor usually found in the subungal region. An extra-digital glomus tumor often poses a diagnostic dilemma. We present a patient with severe thigh pain with hyperesthesia. The diagnosis was finally made through histopathology. This case suggests that glomus tumor should be considered in the differential diagnosis in such a scenario.

Presentation

A 30-year-old woman presented to our outpatient clinic with the complaint of pain on her right mid-thigh. The pain had started insidiously 6 years earlier, was constant with hyperesthesia of the overlying skin, was aggravated by movement or touch and reduced by rest, and had increased in severity over the past 2 months. The patient had difficulty walking due to the pain.

Physical examination revealed marked wasting of the quadriceps muscles of the right thigh, especially the vastus medialis obliquus. Although no obvious mass was visible or palpable, the patient exhibited exquisite tenderness at a point on the medial aspect of the mid-thigh. The overlying skin was normal without any redness or evidence of inflammation. Range of motion of the right hip and knee were within normal limits. Neurological examination of the right lower extremity was normal.

Plain radiographs, ultrasound, and MRI scan were obtained and interpreted. The plain radiographs and ultrasound of the right thigh in both anteroposterior and lateral views were normal. The MRI scan of the right thigh (Figures 1a-b) showed marked atrophy of the vastus medialis, intermedius and lateralis muscles. T2- weighted and STIR images showed increased signal intensity in these muscles. A small focal hyperintense lesion adjacent to the distal medial femoral diaphysis deep to the vastus medialis muscle was seen.

Management

An open excision biopsy (Figure 2) was performed through the medial approach, with the goal of establishing the diagnosis and relieving pain. Surgical exploration of the right thigh revealed a well-defined reddish nodular mass (Figure 3) in the substance of the vastus medialis obliquus adjacent and adherent to the periosteum. The mass was resected and sent for histopathologic examination.

Macroscopically, the resected tumor was dark red, measured 3.5 x 1.6 cm, and was friable in consistency. (Figure 4). Histopathologic examination showed a solid proliferation of round to cuboidal cell arranged in sheets, arising from the wall of intervening blood vessels. Focally, the cells were concentrically arranged around the blood vessel and had uniform to mildly pleomorphic round nuclei with acidophilic cytoplasm. Some mitotic activity and apoptotic bodies were also seen (Figures 5a-b).

The diagnosis of glomus tumor was made based on the clinical, MRI, and histologic findings. Pain relief was immediate and complete after surgical excision of the mass, and the patient was ambulating without symptoms at 6 months follow-up.

Figure 1b. Sagittal STIR image of MRI scan shows an inhomogenous and hyperintense lesion within the substance of the vastus medialis obliquus, extending up to but not breaching the underlying periosteum.

Figure 2 .Planned incision over the right mid thigh.

Figure 3. Surgical exploration of the right mid-thigh from the medial approach revealed a reddish tumor within the mass of the vastus medialis muscle.

Figure 4. The reddish vascular tumor measuring 3.5 x 1.6 cm resected from the mass of vastus medialis muscle of the right thigh.

Figure 5a. Histologic section of the biopsy specimen shows solid proliferation of round to cuboidal cells in sheets that arise from the wall of intervening blood vessels (stain, hematoxylin and eosin; original magnification, X 100).

Figure 5b. The cells have uniform to mildly pleomorphic round nuclei and acidophilic cytoplasm. Some mitotic activity and apoptotic bodies are also seen (stain, hematoxylin and eosin; original magnification, X 400).